In various medical procedures, one or more surgical instruments may be used to puncture or penetrate body tissue. The body tissue may be penetrated in order to insert the instrument into a body cavity such as for example the abdominal cavity. Throughout the present application, the terms penetrating, piercing and puncturing and formatives thereof are used interchangeably. For example an instrument known as a trocar that generally comprises a sharp pointed instrument, may be used to penetrate the abdominal wall to create an access hole therethrough into the abdominal cavity. In another example, an instrument known as a Veress needle or insufflation needle may be used. Veress-type needles use a hollow, blunt inner needle capable of fluid passage, and to carry insufflating gas into the abdominal cavity. A stopcock and valve assembly is connected to the inner needle. The inner needle and valve assemblies are pushed rearward by resistance on the needle end and are biased forward by a spring when the resistance is removed. Thus, Veress needles generally comprise a hollow outer needle having the end opposite the pointed end rigidly secured to a handle or a handle-like housing. A tube or hollow needle or stylet illustratively is slidably carried or disposed within the hollow needle. One end of the tube is typically secured to one end of a piston-like hollow plunger slidably retained within a plunger cylinder formed in the handle or handle-like housing. The other end of the plunger is typically attached to one end of a bias member such as for example a spring, the other end of which is connected to the top end of the plunger cylinder or other handle portion. A centrally located axially directed hole through the housing connects the interior of the plunger cylinder to a port at the end of the housing for receiving a stopcock, petcock or valve mechanism. The other end of the tube typically projects beyond the needle point, with the tube having a gas exit hole through the side of the tube proximate the tip. The tube is oriented within the needle to insure that the gas exit hole of the tube is not blocked by the needle when the tubing end is protruding from the needle via the spring biasing. The free or protruding end of the hollow tube is closed off, typically via a plug.
Needles to create pneumoperitoneum are used to insufflate the abdominal cavity to facilitate endoscopic examination and surgery. Laparoscopic surgical procedures require that a fluid or gas, such as carbon dioxide, be introduced into the abdominal cavity. This establishes pneumoperitoneum wherein the peritoneal cavity is sufficiently inflated for the insertion of trocars into the abdomen. The fluid may be introduced using a Veress or insufflation needle. A Veress-type pneumoneedle has a spring-loaded, blunt tipped inner needle contained within a larger diameter piercing needle. The larger diameter needle is hollow and allows for passage of the blunt needle therein. In using such a needle a physician or user illustratively pushes the free end of the tube against the body tissue, muscles and/or membranes forming the cavity wall of for example the abdomen of a patient. Once the Veress-type needle penetrates the abdominal wall, and enters the body cavity, the resistance against the end of the Veress-type needle is removed, so that the spring force causes the blunt needle or tube to move forward, to extend beyond the sharp tip of the outer needle. This allows the needle to enter the body without puncture or laceration of any abdominal structures. In other words, the tube retracts against the spring biasing, permitting the relatively sharper needle end to be forced for example through the abdominal wall into the abdominal cavity, whereafter the free end of the relatively blunt inner tube pops out or extends from the relatively sharp needle via the spring biasing, thereby exposing the gas exit hole or aperture. This, of course, assumes that the needle is in an open area of the illustrative abdominal cavity or other body cavity, and is not pushing against some other body tissue such as for example an internal organ or muscle, which would prevent the inner tube from so popping out or moving to its extended position relative to the needle. The physician can then connect a gas line to the valve or petcock, and cause gas to enter into the Veress needle, pass through the tube and exit out of the gas exit hole of the tube into the abdominal cavity for insufflating the abdominal cavity. Alternatively, fluid can either be forced into or sucked from the abdominal cavity or other body cavity through use of the Veress needle.
If the needle goes beyond the peritoneum, the needle may perforate the stomach, small bowel, colon, bladder, or major vascular structures, the consequences of which can be fatal. The purpose of the spring-loaded safety tip of the Veress needle is to minimize the risk of visceral injury by covering the sharp tip once it has penetrated the peritoneum and reached a void. Generally, the surgeon relies on tactile senses to determine the proper placement of the needle by recognizing when the needle is inserted through the fascia and then through the peritoneum. However, this technique is often unreliable. It is sometimes difficult for a user, physician or surgeon to ascertain when the internal cavity wall has been breached by the Veress needle or trocar. Typically, the only indication is a reduction in the amount of resistance felt by the surgeon, with perhaps a mechanical vibration or sound caused by the forward movement of the spring biased needle or stylet once the internal cavity has been breached. Various devices have been developed to provide a more positive indication of when the cavity wall has been breached. These devices typically utilize visual or audible signals.
Some relevant examples of Veress needle and trocar instruments include Bauer et al., U.S. Pat. No. 4,379,458; Yoon, U.S. Pat. No. 4,535,773; Moll, U.S. Pat. No. 4,601,710; Moll et al., U.S. Pat. No. 4,654,030; Warring, U.S. Pat. No. 4,808,168; Adair, U.S. Pat. No. 4,869,717; Lander, U.S. Pat. No. 4,902,280; and Holmes, U.S. Pat. No. 4,931,042; Kulkashi et al., U.S. Pat. No. 5,098,388; Sewell, Jr., U.S. Pat. No. 5,290,276; Smith et al., U.S. Pat. No. 5,256,148; Scarfone et al., U.S. Pat. No. 5,669,883; Dennis, U.S. Pat. No. 5,853,392; and Buncke et al., U.S. Pat. No. 6,245,091; the disclosures of all of which are now expressly incorporated herein by reference.
After establishing pneumoperitoneum, the next step in laparoscopic surgery involves the insertion of a trocar into the abdominal cavity. It is through this first trocar that an endoscope is inserted into the abdominal cavity to provide the surgeon with a view of the rest of the operation. Trocars are similar to the Veress needle in that they are also equipped with a spring-loaded safety shield to avoid visceral injury. Trocars, like Veress needles, are inserted using a sudden thrust of the pointed tip into the abdomen. Therefore, as is true with the Veress needle, placement of the trocar is also vital, and the reliance of the surgeon on mere tactile senses for proper placement can be fatal.